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Neuroanatomy > Limbic System/Hypothalamus (2) > Flashcards

Limbic System/Hypothalamus (2) Flashcards

1
Q

The function of the limbic system is what?

A

to reconcile higher level information (from association cerebral cortex) with more basic drives (from subcortical structures) to learn from past experiences, make immediate choices and formulate long term plans

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2
Q

what is the function of the limbic association cortex?

A

conveys highly processed sensory information which is further processed by the hippocampus (in encoding sensory impressions into long-term memory) and the amygdala (to link sensory information with emotional responses)

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3
Q

what is in the prefrontal cortex? Where does it project? Where does input come from?

A

areas of frontal lobe not contained in motor or premotor cortex; striatum; somatosensory cerebral cortex, the dorsomedial and anterior nuclei of the thalamus, and the ventral tegmental area (VTA).

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4
Q

What is the function of the dorsolateral frontal cortex? Damage here can cause what?

A

Important in attention, abstract thought and planning (executive function); reduced abilities to organize information and shift strategies in a changing environment.

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5
Q

What is the function of the ventraomedial frontal cortex and orbitofrontal cortex? Damage here can cause what?

A

inhibition of inappropriate behavior; disinhibition - impulsiveness and disregard for others

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6
Q

The cingulate gyrus receives input from where? Projects to where?

A

sensory cortex, prefrontral cortex, the thalamus (anterior nucleus and nociceptive cells); entorhinal cortex

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7
Q

What is the function of the cingulate gyrus? Damage here can cause what?

A

cingulate cortex is though to mediate the emotional correlates of pain (sadness)
anterior cingulate cortex- thought to play an esp. important role in learning (error detection and reward-based decision making); memory disorders

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8
Q

Hippocampal formation includes what? Receives dopaminergic input
from where?

A

subiculum (transition cortex, layers 3-6), dentate gyrus (archicortex, layers 1-3) and hippocampus proper (archicortex, layers 1-3); ventral tegmental area

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9
Q

The cingulum carries input from where to where?

A

cingulate gyrus to entorhinal cortex and orbitalfrontal gyri to parahippocampal gyrus

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10
Q

The perforant pathway conveys information from where to where?

A

pyramidal neurons in layer II of the

entorhinal cortex to the dentate gyrus and CA3 of the hippocampus proper

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11
Q

The alveal pathway conveys information from where to where?

A

neurons of layer III of the entorhinal cortex to

CA1 the hippocampus

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12
Q

The hippocampus proper can be further subdivided into what four regions?

A

CA1- closest to the subiculum, CA2, CA3, CA4- closest to the dentate gyrus

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13
Q

Cholingergic neurons in the septal nuclei project to where? The hippocampus proper projects to where via what?

A

hippocampal formation; septal area via precommissural fibers of the fornix

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14
Q

Granule cells of the dentate gyrus projects to where via what?

A

CA3 of the hippocampus proper via mossy

fibers

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15
Q

CA3 neurons of the hippocampus proper project to where via what?

A

CA1 neurons via Schaefer collaterals

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16
Q

CA1 neurons of the hippocampus proper project to where?

A

subiculum

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17
Q

The subiculum projects to where via what?

A

mamillary bodies via the columns of the fornix; entorhinal cortex.

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18
Q

What is long term potentiation?

A

High frequency sequence of stimulutions of the perforant pathway, massy fiber pathway or Schaffer collaterals can result in long lasting enchancement of excitatory potentials in the hippocampal neurons

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19
Q

LTP is thought to involve what?

A

an increase in calcium influx through NMDA receptors; calcium activation of calmodulin and the cognitive kinases; retrograde messenger, perhaps nitric oxide (NO) or cell adhesion proteins, acts on the presynaptic neuron

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20
Q 
LTP and the
cognitive kinases (in both the presynaptic and postsynaptic neurons) are thought to enable what?
A

learning and memory by enhancing synaptic transmission between neurons for relatively long periods of time

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21
Q

What are the cognitive kinases in LTP?

A

calcium/calmodulin-dependent protein kinase (CaMK), protein kinase A (PKA), protein kinase Cs (PKCs) and tyrosine kinases

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22
Q

What is long term depression?

A

Weakening of synapses due to postsynaptic receptor density, Weakening of synapses due to postsynaptic receptor density, may be involved in forgetting or negative feedback that regulates LTP.

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23
Q

The fornix consists of axons related to What two structures?

A

hippocampus proper and subiculum

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24
Q

Axons of the fornix initially form what? this coalesces into what?

A

alveus (white matter covering hippocampal formation), fimbria (where the axons collect before leaving the hippocampal formation),

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25
Q

Axons which originate in the hippocampus proper leave the body of the fornix at the level of what? Where do they terminate?

A

AC, travel dorsal to the AC, septal area as the

precommissural fornix

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26
Q

Axons which originate in the subiculum leave the body of the fornix at the level of what? Terminate where?

A

AC, travel ventral and descend in the columns of the fornix into the diencephalon to the mammillary nuclei

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27
Q

The mammillary nuclei project to where via what?

A 
mammillothalamic tract (MTT) to the anterior
nucleus of the thalamus
28
Q

The anterior nucleus of the thalamus projects to where via what?

A

cingulate gyrus via the anterior limb of the

internal capsule

29
Q

The amygdala receives input from where?

A

olfactory bulb (via lateral olfactory stria), entorhinal cortex and has reciprocal connections with the frontal and temporal neocortex

30
Q

The amygdala projects to where via what path?

A

Ventral amygdalofugal pathway to lateral hypothalamus - direct route. Stria terminalis to ventromedial hypothalamus (VMH), septal area via the stria terminalis, dorsomedial nucleus of the thalamus which in turn projects to frontal lobe association cortex

31
Q

What is the function of the amygdala?

A

Fear learning, involved in feeding and reproductive behavior.

32
Q

Patients with damage to the amygdala have what difficulties?

A

cannot discriminate fearful facial

expressions from other emotional expressions. However, they can identify different people.

33
Q

What is an uncinate fit?

A

Involvement of uncus and underlying amygdala. Strange unpleasant odor and feeling of unreality

34
Q

What is Klüver-Bucy syndrome?

A

rarely in humans; extensive, bilateral damage to the anterior temporal lobe, esp. amygdala. Symptoms- placidity (apathy), hyperorality, hyperphagia, hypermetamorphosis (tendency to react to every visual stimulus), visual agnosia (can see but not recognize what an object is) and hypersexuality

35
Q

What are causes of Klüver-Bucy syndrome?

A

herpes simplex encephalitis, brain surgery (usually for epilepsy), trauma, stroke and
neurodegenerative diseases

36
Q

The nucleus accumbens receives input from where? What system is this?

A

Dopaminergic neurons in the ventral tegmental area (VTA) of the midbrain, amygdala, prefrontal cortex; mesolimbic

37
Q

The nucleus accumbens projects to where? What system is this?

A

ventral pallidum, which projects to dorsomedial nucleus of the thalamus which projects to the prefrontal cerebral cortex; mesolimbic

38
Q

What is the function of the nucleus accumbens?

A

Reinforcing effects of food, sex and other stimuli- mesolimbic system, Addictive drugs increase dopamine in nucleus accumbens; stimulated in an attempt to treat depression; stimulated when patients experience the placebo effect

39
Q

The hypothalamus can be divided into what three major regions?

A

anterior, tuberal and posterior

40
Q

What are the subdivisions of the anterior hypothalamus?

A

preoptic area (POA, not part but funct. related), Suprachiasmatic nuclei (SCN), Supraoptic nuclei (SON), Paraventricular nuclei (PVN)

41
Q

POA is located where? Consists of what?

A

below anterior commissure and rostral to the supraoptic region of the hypothalamus; MPOA contains gonadotrophin-releasing hormone (GnRH) neurons- axonsproject to the median eminence

42
Q

Suprachiasmatic nuclei (SCN) is located where? Receives input from where? Projects to where?

A

above the optic chiasm at the base of the 3rd ventricle, direct retinal input, area just ventral to the paraventricular nucleus

43
Q

Supraoptic nuclei (SON) is located where?

A

caudal to the preoptic area, dorsal to the optic chiasm

44
Q

SON consists of what?

A

magnocellular neurons containing vasopressin (anti-diuretic hormone) or oxytocin.

45
Q

SON projects to where?

A

posterior pituitary gland and releases vasopressin and oxytocin into the general circulation

46
Q

Where is the paraventricular nuclei (PVN)?

A

dorsal to the suprachiasmatic nuclei in close proximity to the third ventricle

47
Q

What does the PVN contain?

A

magnocellular (ADH and oxytocin) neurons and parvocellular neurons (TRH, CRH) which project to the posterior pituitary gland or median eminence, neurons- axons project to brainstem and IML cell column of spinal cord via the medial forebrain bundle and dorsal longitudinal fasciculus.

48
Q

What are the components of the tuberal hypothalamus?

A

VMH, arcuate nucleus,

49
Q

VMH is located where? receives input from where?

A

dorsal to the arcuate nucleus, input from amygdala

50
Q

Arcuate nucleus is located where?

A

close proximity to the median eminence, directly dorsal to the median eminence and pituitary gland.

51
Q

Arcuate nucleus is contains what?

A

neurons which produce a variety of different molecules which are released into the median eminence and transported to the anterior pituitary gland; including dopamine, GHRH

52
Q

Mammilary nuclei are in what portion of the hypothalamus? Receive input from where? Project to where?

A

posterior; hippocampal formation via the fornix, anterior nucleus of the thalamus via the mammilo-thalamic tract

53
Q

What are thew 2 main fiber bundles that run through the hypothalamus?

A

Medial forebrain bundle and Dorsal longitudinal fasciculus

54
Q

What is the Dorsal longitudinal fasciculus?

A

axons from neurons within the PVN project to PS CN nuclei and the IML cell collumn of spinal cord (symp); Reciprocal connection between the periaqueductal gray and tegmentum of the midbrain with medial hypothalamus; allows communication of the hypothalamus with reticular formation

55
Q

What is the Medial forebrain bundle?

A

Diffuse group of axons found in lateral hypothalamus, Cell bodies in septal area, lateral hypothalamus, locus ceruleus and piriform cortex; terminate in: hypothalamus, midbrain tegmentum,amygdala, septal area, dorsal nucleus of vagus and raphé nuclei.

56
Q

What is the role of the hypothalamus?

A

neuroendocrine, circadian rhythms, feeding regulation, ANS

57
Q

What role does the hypothalamus play in neuroendocrine?

A

Small neurons produce factors (GHRH, TRH, CRH, GnRH, SS and dopamine) which are transported to the median eminence, released and carried to the ant. pit. by portal vessels; SON and PVN project to post pit (ADH, oxytocin)

58
Q

What role does the hypothalamus play in circadian rhythms?

A

suprachiasmatic region- highly expressed gene for circadian regulation, acts as pacemaker of rhythm; pineal gland- secretes melatonin primarily at night as a result of an indirect projection
from the SCN

59
Q

What role does the hypothalamus play in feeding regulation?

A

VMN- satiety, receptors for glucose; lateral- reg hunger; VMN- receptor for leptin (protein secreted by fat cells, may reg body weight)

60
Q

What role does the hypothalamus play in ANS?

A

Input: Visceral info- from solitary nucleus, contains thermoreceptors and osmoreceptors; Sensory info- reticular formation (integrated, pain), Emotional- septal nuclei, amygdala and hippocampus
Output: project directly to preganglionic symp and PS neurons, or indirect projects to reticular formation

61
Q

Dopamine in the ant. pituitary does what?

A

inhibits release of prolactin from the anterior pituitary gland.

62
Q

Somatostatin does what in the ant. pituitary?

A

inhibits the release of growth hormone from the anterior pituitary gland and
thyroid-stimulating hormone (TSH)

63
Q

Growth hormone releasing hormone (GHRH) does what?

A

stimulates the release of growth hormone

from the anterior pituitary gland

64
Q

Corticotropin-releasing hormone (CRH) stimulates what?

A

release of adrenocorticotropic hormone (ACTH) from the anterior pituitary gland.

65
Q

Thyrotropin-releasing hormone (TRH) stimulates what?

A

release of thyroid-stimulating hormone (TSH) and prolactin (PRL)

66
Q

Gonadotropin releasing hormone (GnRH) stimulates what? Dysfunction of these neurons can cause what?

A

release of follicle stimulating hormone (FSH) and luteinizing hormone (LH):prevent the onset of puberty (Kallmann’s syndrome). After puberty onset, disrupt reproductive function

Neuroanatomy (17 decks)

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